Cached references set in awake aren't persisting

Hi. I have an interesting bug probably resulting in an over sighted "gotcha".

I have a script "A" with some variables

 Material myMaterial; // private material reference
 public Renderer myRenderer; // public renderer reference assigned in inspector

Its awake function:

 void Awake()
 {
     myMaterial = myRenderer.material;
     Debug.Log(myMaterial); // this is not null
 }

It has another function called DoStuff

 public void DoStuff()
 {
     Debug.Log(myMaterial); // this shows as null (details below)
     myMaterial.color = new Color(blablabla);
 }

Then I have another script "B" that accesses DoStuff in its Start function

 void Start()
 {
     aScript.DoStuff(); // I get an error that myMaterial is not set in "A"
 }

more details: i have 2 scenes that make use of these two scripts.. in one scene i get no error but i get the error in the other scene because the script execution order seems to be different.

but script order execution shouldn't matter because all Awake() functions are called before any Start() functions.

So the order in the scene where there is the reference error is as follows:

 A.Awake()
 B.Awake()
 A.Start()
 B.Start()

in the scene where there is no bug uses the following order

 B.Awake()
 A.Awake()
 B.Start()
 A.Start()